Shrimp peeling machinery has been introduced into the art and is now commercially and conventionally used in the peeling of shrimp because of the high alternative labor cost of peeling shrimp by hand, particularly in the case of smaller sized cold water shrimp and shrimp of the Pandalus species. The following patents are representative of the nature and state of the art of roller type shrimp peeling machinery.
U.S. Pat. No. Re. 26,971, Oct. 20, 1970, James M. Lapeyre, is directed to roller type shrimp peeling apparatus which is commercially available in the shrimp peeling industry. This apparatus has peeling roller sets with lower power rollers interacting with intermediate upper channel forming rollers and smaller diameter insert rollers interacting between nips formed between the power rollers and intermediate rollers.
Insert roller improvements are set forth, for example, in U.S. Pat. No. 3,704,484, Dec. 5, 1972, James M. Lapeyre, et al., which provide for better peeling action of the shrimp by means of rough sharp knife-like surfaces on the insert rollers. These roughened rollers however may decrease the yield of usable output shrimp meat by abrasion of the surface meat. Gentler action can be chosen by the surface texture of the rollers.
In general, such peeling apparatus has been designed for maximizing throughput of shrimp being peeled, and thus the roughened insert roller surfaces peel more shrimp faster. In that respect, it is also known from the prior art that the peeling is dependent upon the interaction such as the entry angle between the respective rollers and characteristics of the peeling nips between the rollers as defined by, for example, the diameters of the insert rollers. Thus, for establishing characteristics of commercial lines of peelers, the rollers have been designed in general to maximize peeling throughput of a significant range of shrimp species and sizes as found characteristic in the shrimp peeling industry. Changes in adjustable operating parameters take into account conditions found at local shrimp peeling sites for choosing best available operating conditions of the shrimp peeling machinery.
Prior art shrimp peeling machines have thus provided significant advantage through lower peeling cost and higher peeling quantities. However, to produce acceptable output product quality, the peelers needed to provide cosmetically acceptable shrimp along with the high throughput volume. Thus, prior art shrimp peeling machinery considered cosmetic features for producing an output product that looked good, as well as on features that improved the throughput quantities available. Some attention has also been given to special problems introduced in peeling smaller sized shrimp, cold water shrimp and particular varieties such as Pandalus shrimp in order to solve problems that appeared in the industry. Thus it was known, for example, that some shrimp could be better peeled if cooked at the peeling site and introduced hot into the peeler apparatus.
However, there remains a significant problem with prior art shrimp peeling machinery in that there has been a prior art tendency to aggressively tear off the shells and scrub meat off a roughened peeled shrimp surface to better the throughput efficiency of production. This means that in commercially available peelers of the prior art, a significant loss of usable output shrimp meat product has been tolerated in peeling machinery. However, at the prices obtained from the peeled shrimp, the loss of usable output shrimp meat results in large losses of potential profits in the shrimp industry.
Accordingly it is a primary object of this invention to increase the output yield of usable shrimp meat obtainable with shrimp peeling machinery of the prior art.
This objective, however, introduces great challenges because of the many factors that affect the yield of output meat. Thus, consider that in the machinery factors such as the roller surfaces, the water flow, the temperature and cooking conditions, the aging and wear of the machinery, the throughput volume, the residence time in the peeler, the water flow conditions, the particular peeler design characteristics and spacing or tolerance adjustments, etc. all affect the output yield of usable shrimp meat.
Factors affecting the output meat yield are still more complex because of varying conditions in the shrimp product also. Thus, many variable conditions of the shrimp affect output yield of shrimp meat, such as size, the particular shrimp growing history which varies with catch or school, the location, the species, the aging when peeled, the peeling temperature, the storage history after catch including freezing and thawing conditions, and cooking conditions, etc. This complexity and the interactivity of such factors have made it impractical in the past to investigate or isolate what, if any, methods or equipment changes could in general significantly improve the output yield of usable shrimp meat over such wide ranges of products, machinery and conditions. Because of the interaction of product costs and peeling costs an improvement in output yield is particularly desired in some manner that did not significantly decrease the throughput volume of peeled shrimp. Furthermore, any attempts to optimize conditions of engineering design or processing methods that might have been made at particular peeler installations where restricted ranges of products and conditions exist, if successful, could not be applied in general to shrimp peeling machinery design or methods of peeling to assure results over a significant range of conditions generally found throughout the shrimp peeling industry, which must be the basis for a commercially acceptable production peeler.
Accordingly it is a more specific object of this invention to provide improved apparatus and methods for increasing the yield of usable output of shrimp meat valid for a wide range of conditions actually encountered in the industry.
Other objects, features and advantages of the invention will be found throughout the following description, drawings and claims.